Tuesday, October 18, 2005

Creation of PCB (part 2)

This post is a continuation of the creation of the bottom side of my theremin circuit board. With that said, let's begin! [see materials from previous post]

After I silkscreened the board, the magic began to happen.
I dropped circuit board with the paper adhesed into a large bowl with enough water to submerse the board, and let it sit for about 10 minutes as the paper crumbled away.

Upon extraction from the bowl, and rubbing the remainder of the paper off the PCB, you should get a board that looks like this:

The brighter white segments of the traces are where I used a white-out pen (after soaking the board) to protect areas that did not transfer properly. For the etching process, I used the same bowl. I emptied out the water and poured in half a bottle of Radioshack ferric chloride Etchant. The object here was to ensure that the copper board had ample room above and below to sift the copper away.

After rocking the bowl slightly from side to side for about 30 - 40 minutes, I disposed of the etchant solution in the toilet and rinsed my board with tap water. The board looked okay, but the back of it had some copper remaining. I re-soaked it in etchant, using the other half of the bottle, and still could not remove all the copper from the non-silkscreened side.

I used these neat little tools with the Dremel to remove the white residue from the protected copper traces, but a fingernail would suffice.

The hole-drilling occurs now. Somehow a friend with much more skill in PCB construction than I shows up and volunteers his skill to drill all the holes with a 1/16" drill bit. I would recommend a smaller bit if at all possible!

After being unsuccessful twice at removing all the copper from the other side of the circuit board, I decided that using the Dremel to sand off the copper would be the most prudent thing to do at this juncture.

Will this be a good idea? Find out in the follow up post tomorrow, when I show my success at silkscreening the board's component side.


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